Sir Henry Slingsby is believed to have worn this shirt of finely woven linen at his execution at the Tower of London on the 8th June 1658. He was beheaded and his friends brought his body back to Knaresborough, for burial at the parish church. A simple marble slab, said to have come from St Robert's Priory in Knaresborough, covered his tomb.
Sir Henry was from Red House, Moor Monkton, North Yorkshire and supported the Royalist side during the English Civil War. His family had a close association with Knaresborough. In 1644 he was involved in the Royalist defence of York and probably the following Battle of Marston Moor, where an allied army of Parliamentary and Scottish troops led by Sir Thomas Fairfax and Lord Manchester defeated the Royalists.
Sir Henry sold his Red House estates in 1650 to other family members, fearful of having his property confiscated by the Parliamentarians.In 1654 he was involved in a demonstration by hundreds of Royalists to commemorate the Battle of Marston Moor.He was arrested at Red House in 1655 on suspicion of plotting to take Hull for the Royalists. He was taken to London for his trial for High Treason and sentenced to death on June 2nd 1658.